Hi cln,
I am sorry that you had such a bad nightmare:( I have had some really bad ones as well...and they do tend to stick with you for a day or so.
Sometimes I even feel like I have a 'nightmare hangover'...that's the only way I can describe it. I feel kind of weird and disconnected the day after, and my mind keeps returning to the disturbing images and feelings from the dream.
I don't know if this will help...but I have a site that I like to look at that explains a lot of our dream symbolism. Sometimes just knowing why we have the dreams/nightmares that we do can go a long way in diffusing the fear.
Take a look if you like. I keep it in my favorites so that if I get woken up with a memorable dream...good or bad...I can see how it is interpreted.
http://www.dreammoods.com/dreamdictionary/n.htm
I hope you have a peaceful sleep tonight!
S.C.